Disk Drive Suspension Having Stamped Base Plate Distal Tip

ABSTRACT

A suspension baseplate is stamped at its distal end to which the load beam is mounted. The stamping operation smoothes out roughness in the edge of the baseplate and lowers its height slightly so that, along the line on the baseplate which last contacts the load beam as the load beam is leaving the baseplate, that line on the baseplate is smooth and free of burrs and similar defects. By eliminating burrs on the surface to which the load beam is mounted, variations in the pitch and twist of the load beam are reduced.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplication No. 62/152,930 filed Apr. 26, 2015, the disclosure of whichis incorporated by reference as if set forth fully herein.

BACKGROUND OF THE INVENTION 1. Field of the Invention

This invention relates to the field of suspensions for disk drives. Moreparticularly, this invention relates to the field of a disk drivesuspension whose baseplate has a stamped distal tip.

2. Description of Related Art

Magnetic hard disk drives and other types of spinning media drives suchas optical disk drives are well known. Hard disk drives generallyinclude a spinning magnetic disk containing a pattern of magnetic onesand zeroes on it that constitutes the data stored on the disk drive, aswell as a disk drive suspension to which a magnetic head slider ismounted proximate a distal end of the load beam. FIG. 1 shows ageneralized dual stage actuated (DSA) hard disk drive suspension 10including a baseplate or mount plate 20, one or two PZT microactuators14, a load beam 30 including a spring or hinge portion 32 and a beamportion 34, and a flexure gimbal assembly 36 to which a head slider (notshown) carrying a read/write transducer head is attached at the distalend of the beam portion. The read/write head writes data to, and readsdata from, the data medium which is a spinning magnetic disk drive, orpossibly optical medium in an optical disk drive. Baseplate 20 includesboth a mounting portion 21 which is mounted to an actuator arm (notshown) via swage hub 28, and a distal tip 22 to which the hinge 32 istypically spot welded at weld points 38. Typically hinge 32 is formedintegrally with beam portion 34, so typically load beam 30 is understoodto include spring 32. However, spring 32 and beam portion 34 can beformed separately and then welded together. A number of structuralvariations from the generalized construction shown in FIG. 1 arepossible.

FIG. 2 is an oblique view of a the baseplate 20 of FIG. 1. Baseplate 20is typically die cut or otherwise cut in a metal cutting operation froma relatively thick stainless steel plate. In contrast, hinge 32, beamportion 34, and the stainless steel portion of flexure gimbal assembly36 are usually etched from thin sheets of stainless steel.

In standard suspension terminology and as used herein, the term“proximal” means closest or closer to the end of the suspension which ismounted to the actuator arm; in contrast, the term “distal” meansclosest or closer to the cantilevered end of the suspension, i.e., theend of the suspension that is opposite the actuator arm.

SUMMARY OF THE INVENTION

Die cutting and other metal cutting technologies inevitably producecertain types of defects and irregularities at cut edges, such as burrs,dents, rounding, and other irregularly shaped features. Suchirregularities in cut edges will be collectively referred to herein andin the appended claims as “burrs” for simplicity of discussion. FIG. 3is a closeup of the area of baseplate 20 indicated in FIG. 2 at thedistal end of baseplate 20, with the burrs 25 that result from the metalcutting operation shown in exaggerated form. These burrs 25 can causethe load beam 30 to twist or adopt an initial angle that is out ofspecification or renders the completed suspension unable to meet itsfinal twist or angle specification without an additional adjusting step.The distal tip 22 of baseplate 20 is thus an important part of thesuspension assembly, because it affects the starting twist angle of loadbeam 30.

These defects that are artifacts of the metal cutting operation can belargely eliminated, or their effects on the suspension eliminated or atleast ameliorated, by stamping or coining the distal tip 22 of thebaseplate tip before mounting load beam 30 to the tip 22, such that thelast portion of the baseplate tip 22 that load beam 30 touches before itleaves the baseplate 20 is a relatively clean, smooth, and burr-freestamped line. Coining is a process that causes the baseplate material,which is stainless steel in most cases, to be compressed and to flowslightly. The stamped shelf is significantly smoother, flatter, and morefree of the burrs that are artifacts of the metal cutting process bywhich the baseplate was formed, than are other edges which have not beenstamped. Stamping or coining the distal tip of the baseplate thus helpsto eliminate or at least greatly reduce burrs, and thus helps toeliminate one source of variability in the final load beam twist orinitial angle, thus making the manufacturing process more precise,repeatable, and reliable. If burrs occur at the cut edge, the coiningseparates that cut edge from contact with the load beam. Any burrs onthat cut edge do not touch the load beam, and thus do not affect theassembly of the suspension and its final shape. The line of departure ofthe load beam from the mount plate is defined by the coining, not by thecut edge. This increases the accuracy of the suspension and decreasesthe need for after-assembly adjusting such as by mechanical or laseradjusting of the pitch static attitude (PSA) of the suspension.

In one aspect, therefore, the invention is of a suspension for a diskdrive in which the load beam is stamped or coined at its distal tip thusforming a stamped or coined shelf in the distal tip baseplate. Thestamped shelf includes an edge thereof which defines a line of departurewhere the load beam leave the baseplate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a generalized dual stage actuated (DSA)hard disk drive suspension according to the prior art.

FIG. 2 is an oblique view of a the baseplate of FIG. 1.

FIG. 3 is a closeup of the baseplate area indicated in FIG. 2 at thedistal end of the baseplate, with the burrs that result from the metalcutting operation shown in exaggerated form.

FIG. 4 is an oblique view of a baseplate after the distal edge has beenstamped according to an embodiment of the invention.

FIG. 5 is a closeup of the baseplate area indicated in FIG. 4 at thestamped distal end of the baseplate, with the burrs that result from themetal cutting operation shown in exaggerated form.

FIG. 6 illustrates the area of the baseplate shown in FIG. 5, but alsoincluding a load beam mounted on the baseplate, with the load beam shownin phantom.

FIG. 7 is a side elevation view of the baseplate and load beam of FIG.6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 4 is an oblique view of a baseplate 120 according to an embodimentof the invention after the distal tip or end 122 at the distal edge ofhas been stamped. The distal tip 122 is distal of mounting portion 121which is mounted to the disk drive assembly's actuator arm via the swagehub. The stamping produces a flat stamped or coined region 140 thatdefines a smooth and relatively burr-free stamped shelf 128 formed intip 122. Preferably stamped shelf 140 extends all the way from onelateral end 127 of tip 122 to the opposite lateral end 129. The coinedregion 140 defines an edge 142 on which the load beam will be mounted.Preferably an entire lateral width of load beam at spring region 32extends at last partially over the stamped portion 140 of the baseplatealong a line at which load beam 30 last makes contact with baseplate 20.

FIG. 5 is a closeup of the area of baseplate 120 indicated in FIG. 4 atthe stamped distal tip 122 of the baseplate 120, with the burrs 25 thatresult from the metal cutting operation performed on cut edges 26 shownin exaggerated form. Lip 144 begins at edge 142 of the coined region140. A stamped edge 146 at a distal end of the stamped shelf 128 definesa coined distal edge of baseplate 120. Top edge 142 of lip 144 defines aline of departure where spring region 32 last touches baseplate 120 asit extends distally therefrom and over the coined region 140. Thestamping operation has rendered top edge 142 substantially free of burrs25, or at least substantially smoother and flatter than correspondingbottom edge 148 which lies directly below edge 146 and which still hasburrs 25 due to the metal cutting operation. Similarly, edges 142 and146 are substantially smoother and flatter than other cut edges such asedge 26 that have not been stamped.

As utilized herein, terms such as “about,” “substantially,” and“approximately” are intended to allow some leeway in mathematicalexactness to account for tolerances that are acceptable in the trade, orthat would otherwise encompass a functionally equivalent variation.Accordingly, any deviations upward or downward from any value modifiedby such terms should be considered to be explicitly within the scope ofthe stated value.

FIG. 6 illustrates the area of the baseplate 120 shown in FIG. 5, butalso including a spring region 32 of load beam 30 mounted on thebaseplate, with spring region 32 shown in phantom. Spring region 32 islaser spot welded to baseplate at weld points 38. Top edge 142 defines aline of departure where spring region 32 leaves distal tip 122 ofbaseplate 120. The load beam extends at least partially over the coinedregion 140 of the baseplate.

FIG. 7 is a side elevation view of the baseplate and load beam of FIG.6.

In a preferred embodiment the stamping is performed to a depth of 5-35%of the thickness of the baseplate 112, such that the stamped region willhave a thickness of 65-95% a nominal thickness of the baseplate, such asmeasured at an unstamped region adjacent the stamped region or at themounting region 121 of the baseplate. For a typical baseplate of 0.150mm thickness, the stamping would typically be performed to a depth of0.010 mm to 0.050 mm. The position of stamped line 142 can be locatedjust as accurately as cut edge 26. Since stamped line 142 will be freeof burrs, the stamping operation has allowed the twist and initial angleof the load beam 30 to be more accurately controlled, thus reducing theneed for PSA adjust before the suspension is ready to be mounted to theactuator arm.

In another embodiment the load beam may be mounted on stamped shelf 128rather than on top surface 29 of the baseplate, and the stamping is of auniform depth such that the lateral halves, i.e., both the right andleft halves, of spring 32 are at equal heights. That is, a first lateralhalf of the load beam is mounted on a first lateral half of the stampedshelf, and a second lateral half of the load beam opposite the firsthalf thereof is mounted on a second lateral half of the stamped shelf,and first and second lateral halves of the stamped shelf being stampedto substantially equal depths such that the first and second lateralhalves of the load beam lie at substantially equal heights. In anotherembodiment, only one half, for example, the right half, of a baseplatecould be stamped so as to intentionally introduce a vertical offset inone load beam spring relative to the other, for reasons of reducingtrack misregistration as disclosed in U.S. Pat. No. 7,280,316 toMcCaslin et al. and assigned to the assignee of the present application.In another embodiment, both the right and left halves of the baseplateare stamped, but to different depths, also in order to intentionallyintroduce a vertical offset.

The foregoing figures illustrate the invention as applied to a baseplate120 in which PZT microactuators are mounted. The invention is alsoapplicable to suspensions in which the baseplates do not have PZTmicroactuators mounted to them for moving a distal end of the baseplate,such as is the case for suspensions which are not DSA suspensions, orsuspensions in which the PZT microactuator(s) used to effect finemovements of the head slider are mounted somewhere other than on thebaseplate, such as on the load beam or at the gimbal.

More generally, the invention is applicable to any part of a suspensionin which it is desirable and advantageous to make smoother a rough edge,such as for example but not necessarily a die cut metal edge. Such arough edge can be made smoother be stamping a portion of the part thatincludes the rough edge, such as by stamping a small shelf or ledge intothe part, or stamping a slightly rounded or angled portion into thepart. The smoothing created by the stamping helps to not only eliminatesmall mechanical variations in alignment when one part is mounted to thenow-stamped part, but also helps to reduce the possibility of smallmetal particles being fretted or dislodged during operation where aformerly rough (before stamping) portion of a part contacts anotherpart, especially one that moves slightly during operation.

1. A suspension for a disk drive, comprising: a baseplate for mountingthe suspension to an actuator arm; and a load beam mounted to thebaseplate, the load beam supporting a read/write head for reading datafrom, and writing data to, a data storage medium; wherein the baseplatehas a stamped portion thereof that was created by a stamping operation,and the load beam is mounted to the baseplate such that the load beamextends at least partially over the stamped portion of the baseplate. 2.The suspension of claim 1 wherein the stamped portion defines a flatsurface that lies vertically below a location at which the load beam ismounted to the baseplate.
 3. The suspension of claim 1 wherein thebaseplate was formed from a sheet of metal by a cutting operation thatleft the baseplate with burrs at cut edges of the baseplate.
 4. Thesuspension of claim 1 wherein the load beam comprises a beam portion anda hinge portion, and the hinge portion is mounted on the baseplate. 5.The suspension of claim 1 wherein the baseplate stamped portion extendsall the way from a first lateral side of the baseplate to a second andopposite lateral side thereof.
 6. The suspension of claim 1 wherein anentire lateral width of the load beam extends at least partially overthe stamped portion of the baseplate along a line at which the load beamlast makes contact with the baseplate.
 7. The suspension of claim 1wherein the stamping is performed to a depth of between 5 and 35% of anominal thickness of the baseplate.
 8. The suspension of claim 1 whereinthe stamping is performed at a distal tip of the baseplate.
 9. Asuspension for a disk drive, comprising: a baseplate for mounting thesuspension to an actuator arm, the baseplate comprising a baseplatematerial; a load beam mounted to the baseplate, the load beam supportinga read/write head for reading data from, and writing data to, a datadisk; wherein at a departure line on the baseplate where the load beamceases to make contact with the baseplate, the baseplate has a stampedregion in which the baseplate material was stamped thus causing thebaseplate material to be compressed and to flow.
 10. The suspension ofclaim 9 wherein the stamped region defines a flat surface above whichthe load beam is mounted thereby reducing variability in angularalignment between the baseplate and at least part of the load beam. 11.The suspension of claim 9 wherein: the load beam comprises a beamportion and a spring portion; the spring portion is mounted on thebaseplate; and an entire width of the spring portion extends along thedeparture line.
 12. The suspension of claim 9 wherein: the stampedregion of the baseplate defines a stamped shelf, the stamped shelfincluding the departure line; and a spring region of the load beam ismounted above the stamped shelf.
 13. The suspension of claim 9 wherein:the stamped region of the baseplate defines a stamped shelf, the stampedshelf including the departure line; and a spring region of the load beamis mounted to the stamped shelf.
 14. The suspension of claim 12 wherein:the departure line on the baseplate is substantially flatter than anyother non-stamped edge of the baseplate.
 15. A suspension for a diskdrive, comprising: a baseplate for mounting the suspension to anactuator arm; and a load beam mounted to the baseplate, the load beamsupporting a read/write head for reading data from, and writing data to,a data storage medium; wherein: the baseplate has a stamped shelf formedtherein at a distal region of the baseplate; a boundary of the stampedshelf defines a stamped edge thereof; the load beam is mounted on thestamped edge; and the baseplate has at least one cut edge that is thatis rougher than the stamped edge.
 16. The suspension of claim 15 whereinthe stamped edge is substantially smoother than the cut edge.
 17. Thesuspension of claim 15 wherein the stamped edge is located at a topsurface of the baseplate, and the cut edge is located on the baseplatebelow the stamped edge.
 18. The suspension of claim 15 wherein thestamped shelf has a depth that is between 5 and 35% of a thickness ofthe baseplate.
 19. The suspension of claim 15 wherein the cut edge hasburrs thereon, and any burrs on the stamped edge are substantiallysmaller than the burrs on the cut edge.
 20. (canceled)